Automatic diaphragm arrangement for cameras



Dec. 7, 1965 HAUTMANN Re. 25,925

AUTOMATIC DIAPHRAGM ARRANGEMENT FOR CAMERAS Original Filed Nov. 13, 1959Re. 25,925 Reissued Dec. 7, 1965 25,925 AUTOMATIC DIAPHRAGM ARRANGEMENTFOR CAMERAS Heinrich Hautmann, Erlangen, Bavaria, Germany, assignor toP. Gossen & Co., G.m.b.H., Erlangen, Bavaria, Germany Original No.3,122,980, dated Mar. 3, 1964, Ser. No. 852,646, Nov. 13, 1959.Application for reissue May 13, 1964, Ser. No. 377,796

Claims. (Cl. 9564) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

The present invention relates to a diaphragm arrangement forphotographic cameras in which the exposure aperture is adjusted as afunction of the light intensity striking a photoelectric cell, theadjustment of the diaphragm being fully automatic.

It is known to control the exposure aperture of a camera automaticallyin accordance with the light falling on a photoelectric cell, but in thepast such arrangements have been complex and rather bulky.

The object of the invention is to provide an automatic diaphragmadjustment arrangement which is very simple and compact and yet has anespecially desirable mechanical transmission ratio from the measuringdevice to the diaphragm vanes over the entire range of operation.

Another object of the invention is to operate the exposure aperturediaphragms directly by a galvanometcr energized only by thephotoelectric current, thereby providing a simple compact arrangement.

As more fully explained hereinbelow, the automatic diaphragm accordingto the present invention consists of two diaphragm vanes which aremounted centrally or eccentrically, and are operated by a measuringinstrument which is photoelectrically controlled. The two vanes havenear their adjacent ends cut-out spaces which form the exposure apertureproper, and the arrangement is substantially characterized in that theother ends of the diaphragm vanes overlap and have control slots ofsimilar shape arranged so that they intersect in any of their positions.A single control pin extends through the slots at their point ofintersection, said pin being connected to the rotary coil, of themeasuring instrument by means of a lever arm.

By means of this arrangement the assembly of the diaphragm vanes withthe measuring instrument can be made in a very compact unit of thesmallest dimensions, and, on the other hand, the automatic diaphragmarrangement according to the invention operates very satisfactorily overthe entire range of the diaphragm, as far as the mechanical transmissionratio from the measuring device to the diaphragm vanes is concerned. Thetransmission ratio is the same in both diaphragm vanes for each exposureaperture and is largest when the exposure aperture is largest, i.e.,when the diaphragm starts acting.

In the accompanying drawing an automatic diaphragm arrangementconstituting one embodiment of the invention is illustrated by way ofexample.

As seen in the drawing, a base plate 1 is provided for mounting theentire unit. On the base plate a measuring instrument comprising arotary coil mechanism is provided which consists of an iron cylinder 2,a core magnet 3, and a coil 4. The coil 4 is connected by means ofhelical wires to a photoelectric cell, the wires and the cell not beingshown in the drawing. The unit is adapted for insertion into a still ormovie camera.

Connected to the rotary coil is a pointer 5 which moves over thediagrammatically shown scale 6. The coil 4 furthermore has attachedthereto an arm 7 on which is mounted a control pin 8, the function ofwhich is described more fully hereinbelow.

The diaphragm itself comprises two vanes 9 and 10 arranged in twoadjacent parallel planes; both vanes are supported substantially neartheir center as shown. To take up play, the bearings can be finelyadjusted by means of screws 11 and 12. The screws have bearing jewels(not shown in the drawing), and are supported in a bridge member 13which is mounted on the base plate 1 by means of spacing bolts 14.

The lower ends of the diaphragm vanes are cut out as shown at 15 and 16,the cut-outs together forming the exposure aperture proper and beingarranged in the path of the rays of the optical system 17.

The other end of the diaphragm vanes overlie each other and have slots18 and 19, which intersect in any position of the diaphragm vanes. Thecontrol pin 8 extends through slots at the. point of intersection.

In the position shown, the automatic diaphragm has its largest aperture.When a photoelectric cell, to which the measuring instrument isconnected, is illuminated, the coil 4 is rotated in the direction of thearrow 20. During this movement, the diaphragm aperture 15, 16 is more orless closed by means of the pin 8 and the two similarly shaped slots 18and 19, the exact amount of movement and the closing of the aperturedepending on the amount of light falling on the photoelectric cell.

It can be easily seen that the effective lever arm which controls themovement of the diaphragm is smallest at the beginning of the diaphragmrange, i.e., when the exposure aperture is largest. This is true of bothdiaphragm vanes. In this manner one of the objects of the invention isachieved, in that the mechanical transmission ratio from the rotary coilto the diaphragm vanes is the same at every angle of rotation for eachof the two vanes, and is largest at the beginning of the diaphragmrange, that is, when the vanes have to cover the largest path per degreeof movement of the pointer over the scale of the measuring instrument.

The arrangement according to the invention has the advantage, ascompared to presently known arrangements, that there is permitted agreat deal of variability in the spatial arrangement of the measuringdevice. Depending on the space left free by the assembly of the othercamera parts the measuring instrument may be placed to the left or theright of the upper end of the diaphragm vanes; whereby the space for therocking of the vanes obtained within the casing can be made quiteconsiderable. If necessary, in an extreme case, the measuring instrumentcan be so positioned that the iron cylinder of the rotary coil assemblyof a construction similar to the one shown, may be adjacent one of thespacing bolts 14.

I claim:

1. In an automatic diaphragm arrangement for photographic cameraswherein two mounted diaphragm vanes are operated by a photoelectricallycontrolled measuring instrument including a rotary coil, and wherein twoadjacent portions of the vanes are shaped to form the exposure apertureproper; the improvement constituted by other portions of the twodiaphragm vanes overlying each other and having respective control slotsof similar shape which are so arranged that they intersect in everyposition thereof, two separate laterally spaced pivots for mounting saiddiaphragm vanes, a lever arm extending from the rotary coil of themeasuring instrument, and a single control pin fixed to said lever armand extending through said slots at the point of intersection of saidslots for moving said vanes.

2. In an automatically controlled diaphragm arrangement for aphotographic camera, a pair of complementary diaphragm vanes having[similarly] shaped portions at one end defining an exposure aperture,said vanes having respective curved slots in close proximity to theirother ends, one of said vanes overlying the other so that said slotsintersect [at similarly located points thereof] for all operativepositions of said vanes, two separate laterally spaced pivots forrespectively mounting each of said vanes at an intermediate pointthereof, a rotary coil, means for producing a rotation of said coil inresponse to a current supplied thereto, and means including a singlemember connected to said rotary coil and extending through the slots atsaid intersection thereof for rotating said vanes on their respectivepivots at equal rates.

3. Apparatus according to claim 2, wherein said single member includesan arm extending radially from said coil and a pin fixedly mounted onsaid arm and extending through said slots, said pin and said vanes beinglocated relative to each other so that the angular rotation of the vanesrelative to the rotation of the coil decreases as the exposure aperturedecreases.

4. In an automatically controlled diaphragm arrangement for aphotographic camera, a base plate, a pair of complementary diaphragmvanes having [similarly] cut out portions defining an exposure aperture,said vanes having respective similarly shaped slots in another portionthereof, one of said vanes overlying the other so that said slotsintersect [at similarly located points] for all operative positions ofsaid vanes, two laterally spaced pivots for respectively mounting eachof said vanes on said base plate at a point intermediate its slot andcut out portion, current measuring means including a rotary coilrotatable in response to a current supplied thereto, and means includinga single pin connected to said rotary coil and parallel to the axis ofrotation thereof and extending through said slots at the intersectionthereof for rotating said vanes about the pivot points whereby thecurrent measuring means may be provided at other posi tions on the baseplate around the diaphragm vanes.

5. In an automatically controlled diaphragm arrangement for aphotographic camera, a pair of complementary diaphragm vanes having[similar] cut out portions defining an exposure aperture, said vaneshaving respective similarly shaped slots in another portion thereof, oneof said vanes overlying the other so that said slots intersect [atsimilarly located points] for all operating positions of said vanes,means for pivotally mounting each of said vanes at a point intermediateits slot and cut out portion, a current meter including a rotary coilmeans for rotation in response to a current supplied thereto, and meansincluding a single pin fixedly connected to said rotary coil means andextending parallel to the axis of rotation thereof and through saidslots at the intersection thereof for rotating said vanes at ratesrelative to the rotation of said coil means which vary in accordancewith the size of the exposure aperture.

References Cited by the Examiner The following references, cited by theExaminer, are of record in the patented file of this patent or theoriginal patent.

UNITED STATES PATENTS 2,421,499 6/1947 Guedon 9564 FOREIGN PATENTS1,182,695 1/1959 France. 1,193,034 4/1959 France. 1,193,902 5/1959France.

859,892 1/1961 Great Britain.

NORTON ANSHER, Primary Examiner.

p C. B. PRICE, Assistant Examiner.

